As is known with human physiology, the two phases of ventilation include inhalation (air moving into the lungs) and expiration (air leaving the lungs). The scientific principle governing such aspects of inhalation is known as Boyle's law which operates under the principle that air moves from areas of high to low pressure.
Inspiratory muscle exercising and training devices are known and which operate under the principle of limiting air intake during inhalation, the result of width assists in developing lung function and capacity through the development of the muscles responsible for assisting inhalation. Primary among these are the diaphragm and external intercostal muscle groups which operate to expand the space in the rib cage downward (diaphragm) and enlarge the rib cage outward (intercostals).
Accessory muscles, such as including the scalenes, latismus dorsi, pec major-minor, and others are additionally provided and operate to varying deuces depending upon a level of fatigue or limited expulsion experienced with the primary muscle groups. A common occurrence among individuals is when the primary muscle groups are relatively weak in comparison to these and other secondary/accessory muscles and such that the individual is not experiencing maximum lung expansion during exercise, along with experiencing other undesirable side effects including cramping and chest tightness.
One example of an inspiratory muscle training device is depicted in U.S. Pat. No. 6,554,746, to McConnell and when includes a chamber having an opening for the passage of air to be inhaled and exhaled, along with an inlet permitting air to be inhaled to enter the chamber and to pass to the opening. A one-way exhaust valve permits exhaled air entering through the opening to escape from the chamber, and another valve is provided to resist the entry of air to be inhaled into the chamber. The latter valve serves to vary the degree of resistance in dependence upon the volume of air that has passed through the inlet.
Additional examples respiratory exercise devices include the therapeutic device of Norell, U.S. Pat. No. 4,973,047, the device of Carlucci U.S. 2004/0146842, and the devices respectively shown in each of Ericson U.S. Pat. No. 4,221,381 (Ericson) and U.S. Pat. No. 4,739,987 (Nicholson).